Internal combustion engine



Dec. 21, 1943.

H. M. JACKLIN INTERNAL coMBUsTIoN ENGINE Filed Aug. 22, 1941 2sheets-sheet 1 l/lllllll/ Dec. 21, 1943. H. M. JACKLIN INTERNALCOMBUSYTION ENGINE Filed Aug. 22, 1941 2 Sheets-Sheet 2 nlllllilllllmdlu ihnen/Enf.

Patented Dec. 21, 1.943

UNITED STATES PATENT OFF/ICE 2,331,245 INTERNAL coMBUs'rIoN ENGINE iHarold M. Jacklin, La Fayette, Ind. Application August 22, 1941, serialNo. 408,006

(cries-65) 6 Claims.

This invention relates to two-stroke cycle engines of the uniow type. Insuch engines, ports located at opposite ends of the cylinder areuncovered at or near the end of the working stroke of the piston, theburnt gases are exhausted through the ports at one end of the cylinder,

l while air or a mixture of fuel and air is admitted through the portsat the opposite end of the cylinder. y I

Heretofore, engines of this genera-l kind have been of either of twotypes. Inv the rst type, called the opposed piston type, tworeciprocating pistons move oppositely in a single cylinder andrespectively uncover the inlet 'and exhaust ports as they near the endsof the Working strokes. In the other type, there is a .single workingpiston which uncovers cylinder ports at one end of the cylinder as itnears the end of its Workingstroke, while the ports at the opposite endof the cylinder are controlled by a poppet valve. The opposedpiston-type of engine has certain disadvantages because of theproblernsencountered in interconnecting the two working pistons. Thepoppet valve type of engine is open to the objection that relativelylarge forces must be used in order to obtain the necessary quick openingandv quick closing of the valves, and such largeforces entail high unitbearing-pressures and necessitate the use of heavy springs.

It is the object of my invention to produce a two-stroke cycle engine ofthe uniow type which will be free from the above noted disadvantagespossessed by prior engines of this kind. More specically, it is myobject to provide an enginey which may have a single Working pistoncontrolling or aiding in the control of one set of ports and in whichthe other set of portsr will be controlled by valve-operating mechanismwhich will provide a quick opening and quick closingl of the ports anddo so without the imposition of relaf tively large forces.

In carrying out my invention, I employ a cylinder having inlet ports atone end and outlet po'rts at the other. One set of these ports iscontrolled by a reciprocable valving element which may be either apiston or a sleeve, while the other set of ports may be controlled atleastin part by the working piston. The yalving element is reciprocatedin the cylinder by an eccentric operating at the same speed as thecrankshaft of the engine; but instead of connecting the `valving elementdirectly to such eccentric, which would cause the valving `element tooperate withl an approximately harmonic motion, I interpose be'- tweenthe valving element arid the eccentric various forms, as will be morefully broughtout 1 hereinafter.

The accompanying drawings illustrate my invention: cylinder of an engineembodying a piston valve which is under the joint control oftwo'eccentrics; Fig. 2 is a diagram showing movements of the workingpiston and piston valve during the twostroke "cycle of the engine; Fig.3 is a fragmental -view similar to Fig. 1 illustrating the upper end vofa piston-valve engine with a movement-modifying means' embodying asingle eccentric, the valve being shown as open; Fig. 4 is a viewsimilar to Fig. 3 showing the valve closed; Fig. 5 is a sectional viewsimilar to Fig. 1, but showing -a valving element in the form of asleeve operated by two eccentrics; Fig. 6 is a diagram illustratingmovements of the piston and sleeve in the construction of Fig. 5; Fig.'l is a Iragmental view similar to Fig. 5 showing a modified form ofdouble-eccentric sleeve-operating mechanism; and Fig. 8 is a viewsimilar to Fig. 'l illustrating a sleeve-operating mechanism embodying asingle eccentric.

The engine illustrated in Fig. 1 has a working cylinder Il! -provlded atone end with an annular series of ports II and at the I a second annularseries of ports I2.l Either set of these ports may serve as inlet portsand the other as exhaust ports; butit is `preferable in most instancesthat the upper ports be used as For the purpose `of controlling theexhaust ports I2,` a piston valve 20 provided at its lower ,i end with ajunk ring 2'I is mounted for reciprocation in the cylinder II'I in sucha manner that the lower edge of the junk ring will pass Vacross theports I2 and open and close them as the valve 20 reciprocates. Betweenthe valve 20 and piston I5, the cylinder is provided with an opening 25for the receptlonfof a spark plug. or other ignition device, if theengine isof a type requiring igni- Fig. 1 is an axial section through aopposite end with i being such l tion, or for the reception of afuel-injection nozzle, if the engine is of the compression-ignitiontype.

For the purpose of controlling movements of the valve 20, there ismounted above the head end of the cylinder a rotatable main eccentric 30adapted to be driven at crankshaft speed as by means of a train of gearsy3l. Also mounted above the head end of the cylinder is a second orauxiliary eccentric 32 arranged to be driven at twice crank-shaft speed.Connecting rods 33 and 34 serve to connect the eccentrics 30 and 32respectively with pins 33' and 34Vv in the opposite ends of a lever 35pivotally connected at an intermediate point to the valve 20, as througha pivot pin 36. y f

The exact movement imparted to the valve by the two eccentrics and 32will depend upon a number oi factors among which are therespectivethrows of the two eccentrics, their phase-relationship, andthe relation between the distances of the pins 33' .and 34' from the pin36'. Ordinarily, the eccentric 30, which rotates at the same speed asdoes the crank shaft, will lead the crank I'I by an angle between 8 and15, while the eccentric 32 will lead the crank I'I by an angle between16" and 30, sothat the valve 20 will reach its lower dead-center 8 to 15before the working piston I5 reaches its outer (upper) dead-centerposition. The relative spacing of the pins 33 and 34 from thepin 36 mayvary considerably, but I prefer to make the distance from the pin 33'-to the pin 36 between 15% and v50% of the distance between the pins 33'an'd34'.

The diagram shown in Fig. 2 represents the disposition of the Valvingevents within a complete cycle. In this diagram, the line 40 representsthe upper edge and the line 4I the lower edge of the p'orts I2. whilethe line 42 represents the upper edge and the line 43 the lower edge ofthe ports I I. 'Ihe curved line 44 represents the displacement of thelower edge of the junk ring 2I during a complete cycle (360 ofcrankshaft rotation) beginning with Athe working piston I5 atheadenddead center; while the curved line 45 represents displacement ofthe upper end of the working piston I5 during the same interval.Whenever the curved line 44 lies above the horizontal line 4I, the portsI2 will be open, as represented by the shaded area E6; and whenever theline 45 is located below the line 42. the ports II will be open,.asindicated by the shaded area 417. The dotted line 48 shown at the top ofFig. 2 represents approximately what displacement of the lower edge ofthe junk ring 2I would be if the valve 20 were directly connected to asingle eccentric operating at crank-shaft speed.

From a comparison of the full-line 44 and-th dotted-line 48, it will beapparent that during the time in which the lower edgeof the junk ring 2Iis moving across the port I2 its speed is relatively rapid. In order toobtain a port-opening of the same duration with the valve 20 directlyconnected to a single eccentric it would be necessary to reduce greatlythe height, and therefore the are of the exhaust ports I2. It will befurther app rent from Fig. 2 that when the main piston I5 is near theupper limit of itsv movement in the vcylinder the speed of the valve 20is relatively slow. It is when the working piston is near the upper .endof its stroke that working pressures within the cylinder are at theirhighest; and it is advantageous i'or the piston valve 20 and itsassociated Junk ring 2| to undergo as little move-v for the exhaustports to close while the inlet ports v are still open. It is for thisreason that a lead is imparted to the eccentrics 30 and 32; and becauseof the existence of this lead the shaded area 06 in Fig. 2 is displacedto the left from the center of the diagram. From the diagram whichconstitutes Fig. 2, it will be apparent that the opening of the exhaustports I2 would occur about 10 to 15 (of crankshaft rotation) earlierthan does' opening of the inlet ports I I, while closing of the exhaustports I2 would occur from 15 to 20 earlier than closing of the inletports.

The engine illustrated in Figs. 3 and 4 embodies the same portedcylinder I 0, piston I5, and pistonvalve 20 as does the engine shown inFig. 1. In this instance, however, the piston-valve 20 is connectedthrough a link 50 to one arm of a bellcrank lever 5I whose other arm isconnected by a-connecting rod 52 to an eccentric 53 rotating atcrank-shaft speed. As the eccentric 53 rotates, the bell crank 5I.oscillates about its axis and causes reciprocation of the valve 20 inthe cylinder to open and close the exhaust ports I2.

The parts of the mechanism operating the piston-valve 20 of Figs. 3 and4 are so arranged that when that valve is at lower dead center, or inthe position illustrated in Fig. 4, the points of interconnection of thelink 50 with the valve 20 and bell crank 5I will be in approximatealinement with the axis of the bell crank. This arrangement results inimparting to the valve 20 a movement having the same characteristics asis imparted to the valve by the mechanism illustrated in Fig. l-namely,the valve moves relatively rapidly Y While its lower yedge is crossingthe exhaust ports I2 and relatively slowly afterithas covered the portsI2. Moreover, in the arrangement shown in Figs. 3 and 4, when the valve20 is at lower dead center, the heavy cylinder-pressures existing atthat time are transmitted substantially directly through the link50 andbell crank 5I to the bell-crank pivot and are not reected to any greatextent as forces imposed on the connecting rod 52 and eccentric 53.

The engine illustrated in Fig. 5 is of the sleevevalve type. Thecylinder I0 is provided at its opposite ends with two sets of'ports 60and 6l the former of which, located at the lower end of the cylinder,are assumed as before to be intake ports, while the latter are exhaustports. The upper end of the cylinder I0 is closed by a head 62 having adownwardlyextending, centrally located, cylindrical boss 62' somewhatsmaller than the bore of the cylinder I0 in order to provide an annularspace for the reception of the upper end of a sleeve valve 63 withinwhich the working piston I5 reciprocates. The head 62 is providedwithone or more sealing rings preferably including at its lower end arelatively wide junk ring 64. The sleeve 63 extends downwardly through`the cylinder I0 and is provided in the region of the cylinder ports 60with a circumferential series of intake ports 65 and in the region ofthe cylinder ports 6I with a. circumferential series of exhaust ports66. 'I'he opening 25, for

the reception of an 'ignition or fuel-injection device, is in thisengine disposed in the head 62.

For the purpose of reciprocating the sleeve 63 to control the opening-and closing of the intake and lexhau/st ports I employ, as in theengine shown in/Fig. 1, amain eccentric 10 `operating at crank-shaftspeed and an auxiliary eccentric 1l cperatingattwice crank-shaft speed.The

main eccentric may be carriedby the crank shaft of the engine, yand'isso illustrated; while Veilect of movement of the sleeve andpiston uponthe opening and closing of the inlet and exhaust ports. In this diagram,the line 11 indicates the elevation of the lower edge'of the Junk ring65, and the curved line 18/repre'sents vertical displacements of thepiston I5. 'I'he twov equidistant curved lines 19 and 30 representrespectively the displacements of the upper and lower edges of theexhaust ports 66 in the sleeve; while the two equidi'stant lines 8l and32 represent displacements of the upper and lower edges of the inletports 65 in the sleeve. As will be. readily apparent, wheneverthe vline80 lies below the line 11 the exhaust ports '63 will be open, and when#ever the line 18 lies below the line 3| `the inlet ports will beopen.

It :will be noted in'Fig. 6 that the valveoperating mechanism imparts tothe sleeve 63 a move.,

ment similar in character to that imparted to the piston-valve 20 by thedouble-eccentric valve- Flg. 'I I have shown a construction in which 'alever 33. has oneend connectedl to the sleeve 63 and its other Aendpivotally connected to the connecting rod `13, while the connecting rod12 is pivotally connected to an intermediate point ofthe lever.

In the arrangement illustrated in Fig. 8. the sleeve 63 is operated by asingle eccentric 81 rotating at crank-shaft speed andconvenientlymounted directly on the crankshaft. Here, the

lower end of the sleeve is connected through aV link 88`with one end ofa lever 89, whose opposite end `is connected through a connecting rod 93with the eccentric 81. The arrangement of the parts is such thatl as thesleeve approaches the upper end of its'mcvement. where the ports are al1closed, the pcintsgyf pivotal connection of the link 88 with the sleeve63 and lever 89 approach alinement with the axis*about which the leverswings. The position of the parts when. the sleeve is at the upper limitof its movement is indicated in dotted lines in Fig. 8. 'I'hisYarrangement impartsto thesleeve 63 a comparativelyrapid movement whilethe ports are being openedV and closed and a comparatively slowmovement"` after the ports have been closed, and also reduces the forcesto which the eccentric 81 and connecting rod 90 are subjected when thepiston I5 is near thehead end of the cylinder and cylinder pressures arehigh.

4 In all the modifications illustrated in ithe drawing, the movement ofthe valving elem nt,

'whetherit b e a piston or a sleeve, has essenti lly the-same generalcharacter. That is, the move- .mentor the valvingI element is morerapidthan operating mechanism shown in Fig. 1.' That is, 1

during the time lthe working. piston i3 is near the upper limit of its4stroke with all'portsclosed movement of the sleeve 63 is relativelyslow;

In' the case of the inlet ports '35 which are opened and closed byrelative movement iof the sleeve and piston, the relative rapidity ofsleeve movement tends to retard the speed o! port-opening andport-closing; for during' each of these events thesleeve and piston aremoving -in the same direction with the latter moving the more rapidly.However, the speed of the piston-is so much greater than the speed oftheA sleeve, that fthe. increase of ,sleeve-speed which resultsyi'ro'mthe incorporation of my inventiondoes not obwhereas when the sleeve ismoving te open or Qsubjectedto high pressures' close the ports itsmovement is relatively vrapid.

a'harmonic motion would be during valve-opening and' valve-closing, but'is materially slower than a harmonic motion after the ports have oncebeen closed., 4Since the highest cylinder pressures-exist when. theports are closed, the valving .element will move only slightly whilewhich feature resuits-in a -material reduction in, wear. This elementresults fromV modifying the action of an eccentric operating atcrank-shaft speed.

In all embodiments shown, the action of the i eccentric is modiedthrough the employment of a lever which forms part of the mechanism bywhichthe valving element is connected to the eccentric operating atcrank-shaft speed. l In. `the arrangement illustrated in. Fig. l? theelement 35 maybe regarded as a lever of the second cl'ass fulcrumed ,at34', receiving the'joperat-v lat'its point of connection .with'ltheconnecting The eccentrics 10 and 1|,.like the eccentrics 33 and 32 inthe' engine shown in Fig. 1, can be given'leads over. the crank shaftyso as to throw the period in which the exhaust ports ,63 are open aheadof the midpoint of the cycle.

It is not essential in either of the valve-oper?,

ating mechanisms illustrated in Figs 1 and 5 .that the valve beconnected to an intermediate,

point on the lever (35 or 1I) actuated by the two eccentrics; asmovement of the same general character can be imparted to the valve by fconnecting it to one end of the lever. Thus. inl

ing effort, at3'3', and having the load applied to itat 3 3. The element1l in Fig. 5 may also be regarded as alever ofthe second classfulcrui'ned rod 13, receiving. the operating effort through theconnecting rod-12, and having theload apcharacteristic of the movementof the valving plied to it at its point oi' pivotal connection with vthe sleeve 63. On the-same basis, the element 35 in Fig. 7 would be alever of the third class, fulcrumed at its point of interconnection withthe connecting rod 13, receiving the'cperating eifort at an intermediatepoint through the connecting rod 12, and4 having the load applied at:its outer end where it is connected to Athe sleeve. In-all three ofthese arrangements, the' points at which the operatingeilort and theload are respectively applied to the-lever moveback and forth in lineswhich are generally parallel to the cylinder axis:l

'and the lever-fulcrum is reciprocated 'also along a line generally parliel to the cylinder axisand spee at twice crank-shaftYV rapid valvemovement during port-opening and d to produce relatively port-closingand relatively slow valve movement when all ports are closed. s

In the modification of my inventionshown in Figs. 3`and 4 the leverwhich modifies the action ofthe eccentric is the bell-crank I. In' thiscase the fulcrum of the lever-i. e., the axis of the bell-crank--is xed,and modification of the action oi"` the eccentric is obtained by soarranging the parts that the path of the point at which the operatingeffort is applied to the lever is in general ralinement with suchoperating effort throughout the entire range of swinging movement of thelever 5l, while the path of the point at which the load is applied tothe lever is generally perpendicular to the path' of valve movementafter the ports have been closed. In the respect just noted, theconstruction shown in Fig. 8, which also-employs a fixed fulcrum orpivot, is the same as that shown in Figs. 3 and 4. The f ct that theloaded end of the lever (5| or 89) is oving in a direction lgenerallyperpendicular to the path of valve movement during most of the intervalin which the ports are closed makes it possible for movement of thevalve to be relatively slight in comparison with movement of the lever.

As previously noted, the exact shape of the r curve 44 (Fig. 2)representing axial displacement of the valve 2U willdepend upon severalfactors. Because the eccentric 32 rotates at twice the speed of theeccentric 3U, the right-hand end of the Alever 35 will reciprocatevertically twice -whilel the left-hand end of such lever isreciprocating once. If, as the result of the relation between the throwsofthe eccentrics and of the spacing of the pins 33', 34', and 36, theeffect of the eccentric 32 upon movement of the valve 20 is greatenough, the valve may change its direction of movement four timesinstead of twice during each cycle. That is, after moving upwardly for adistance from its lowermost position, the valve may reverse itself andmove downwardly for an interval and then resume an vupward movementwhich continues until the valve has reached the upper limit of movement2| is well vbelow the ports l2 so that the desired valve timing will notbe interfered with.

` The same possibilityof an intermediate and temporary reversal of valvemovement in each half of the cycle exists in the ca'se of thesleevevalve engines illustrated in Figs. 5 and '7 and can in similarmanner be prevented from aiecting the valve-events.

I claim asmy invention:

l. In a' two-stroke cycle internal combustion engine, aworkingcylinderhaving inletports at one end and exhaust ports at the otherend,a working pistonreciprocable in said cylinder and and a pair oflever-operating devices.' said devices and said valve being connected tosaid lever at three points spaced along the lever, said devicesoperating to reciprocate the lever-points to which they are respectivelyconnected, one point at a rate corresponding l to the rate at which thepiston reciprocates and the other point at twice such rate, said leverand operating devices being proportioned to cause said valve to producea complete opening of its associated ports in less than 60 ofcrank-,shaft rotation.

2. In a two-stroke cycle internal combustion engine, a working cylinderhaving inlet ports at arranged to uncover one set of such ports when atthe adjacent end of the cylinder, a crankshaft operatively connected tosaidpiston, a

' said piston, said means including a lever extending generallyperpendicularly to the cylinder axis one end and exhaust ports at theother end, a-

working vpiston reciprocable in, said cylinder and arranged to uncoverone set .ciV such ports when at the adjacent end ofthe cylinder, a valveaxially reciprocable in said cylinder for controlling the other set ofports, and means for reciprocating said valve intimed relation with saidpiston, said means including a lever extending generally perpendicularlyto the cylinder axis and a pair of lever-operating devices, said devicesand said valve being connected to said lever at three points spacedalong the lever, one of said devices operating to reciprocate thelever-point to which it is connected at a rate equal to that at whichthe piston reciprocates and the other of Said devices operating toreciprocate the lever-point to which itis connected at twice such rate,the distance between the points of connection of said lever to saidvalve and the former of such devices being less than the distancebetween the peints of connection ofy the lever to the valve and thelatter of such devices.

3. In a two-stroke cycle internal combustion engine, a working cylinderhaving inlet ports at one endand exhaust ports at the other end, aworking piston reciprocable in said cylinder and arranged to uncover oneset of such ports when at the adjacent end of the cylinder, a valveaxially reciprocable in said cylinder for controlling 'the other set ofports, and means for re` ciprocating said valve in timed relation withsaid piston, said means including a leverI extending generallyperpendicularly to the cylinder axis and a pair of eccentrics one ofwhich rotates at a speed corresponding to that of reciprocation of saidpiston and the other of-which operates at twice suchvspeed, saideccentrics and said valve being operatively connected to said lever` atthreepoints spaced along the lever, the distance between the points atwhich said lever is connected to the valve andthe slower eccentric beingless than the distance ybetween the points at which the lever isconnected to the valve and the faster eccentric.

,4. In a two-stroke cycle internal combustion engine, a working cylinderhaving inlet ports at one end and exhaust ports at the other end, aworking piston reciprocable in said cylinder and arranged to uncover oneset of such ports when at the adjacent end of the cylinder, a valveaxially reciprocable in said cylinder for controlling the other set ofports, and means for reciprocating said valve in timed relation withsaid piston. said means including a lever extending generallyperpendicularly tothe cylinder axis and a pair of eccentrics o ne ofwhich` rotates at a speed corresponding to that of reciprocation of saidpiston and the other of which operates at twice such speed, saideccentrics and said valve being operatively connected to said lever atthree points spaced along the lever, said eccentric and lever being soproportioned to cause said valve to produce a complete opening' of itsassociated ports in less than 60 of crank-shaft controlling the otherset of ports, and means for reciprocating said valve in timed relationwith said piston, said means comprising a valve-operating eccentricrotating at a speed equal to that at which the piston reciprocates andmechanism including a lever operatively interposed between saideccentric and valve for eecting a relative reduction in the eilect ofeccentricmovement upon'valve-movement when the ports controlled by saidvalve are closed and for increasing the eiect of eccentric-movementuponv valve-movement when such ports are being opened and closed by.said valve to an extent sumcient to produce complete'opening of suchports in less than 60 of crank-shaft rotation.

v engine, a working cylinder having inlet ports at one end and exhaustports at the other end, a Working piston reciprocable in said cylinderand 6. In a two-stroke cycle internal combustion arranged to uncover oneset of such ports when at the adjacent end of the cylinder, a crankshaftoperatively connected to said piston, a i

valve. axially reciprocable in said cylinder for controlling the otherset of ports, and means for reciprocating said valve in timed relationwith said piston, said means comprising a valve-operating eccentricrotating at a speed equal to that at which the piston reciprocates andmechanism operatively interconnecting said eccentric and valve foreffecting a relative reduction in the eiect of eccentric-movement uponvalve-movement when the ports controlled by said valve are closed andfor increasing the effect of eccentricmovement upon valve-movement whensuch ports are being opened and closed by said valve to t an extentsuillcient to produce complete opening of such ports in less than 60 ofcrank-shaft rotation.

HAROLD M. JACKLIN.

